Balance Chemical Reactions

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Synthesis Reactions

• Occur when two or more

substances combine to

form one compound.

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Problem 1

N2 + H2 NH3

N

H

2

2

1

36

2

6

3 2

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Problem 2

S8 + O2 SO3

S

O

8 1

2 3

8

8

24

12

24

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Problem 3

N2 + O2 N2O

NO

22

21

2

42

4

2

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Synthesis Reactions

K + Cl2

Sb + S8

Cu + O2

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Synthesis Reactions

Cs + O2

Ag + O2

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Single Displacement Reactions

• Occur when an

uncombined element

replaces an element that

is part of a compound.

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Problem 4

Na + H2O NaOH + H2

NaH

O

1 12 3

1 1

2 2

4 42

2

2

2

2

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Problem 5

Zn + HCl ZnCl2 +

H2 Zn

H

Cl

1 1

1 2

1 2

2

2

2

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Single Displacement Reactions

Zn + FeCl3 +

Cs +H2SO4 +

Fe2O3 + H2 +

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Single Displacement Reactions

Zn + CuSO4 +

Fe + CuSO4 +

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Decomposition Reaction

• A complex substance breaks down into two or more simpler substances.

2H2O 2H2 + O2

AB A + B

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Problem 6

KClO3 KCl + O2

K

Cl

O

1 1

1 1

2

23

2

2

6

2

2

2

3

6

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Problem 7

HgO Hg + O2

Hg

O

1 1

1 2

2

2

2

2

2

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Decomposition Reactions

Al(OH)3 + H2O

CuSO4 + SO3

AuCl3 Au +

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Decomposition Reactions

H2SiO3 + H2O

HNO3 + H2O

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Combustion Reactions

• A hydrocarbon is a

compound containing only

carbon and hydrogen.

• When burned they will

combine with oxygen.

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Problem 10

C7H6O2 + O2 CO2+ H2O

C

H

O

7 1

6 2

4 3

7

7

15

3

6

142

14

12

6

14

6

12

3417

15

34

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Combustion Reactions

CH4 + O2 CO2 + H2O

C2H6 + O2 CO2 + H2O

C6H12O6 + O2 CO2 + H2O

C2H5OH + O2 CO2 + H2O

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Double Displacement Reactions

• An element from each of

two compounds switch

places.

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Problem 8

BaCl2+Al2(SO4)3 BaSO4+

AlCl3

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Problem 9

FeBr2 + K2CO3

FeCO3 + KBr

Note that the subscripts of K and Br have changed in the formulas.

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Problem 9

FeBr2 + K2CO3

FeCO3 + KBr

FeBrK

CO3

112 1

121 1

2

22

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Double Displacement Reactions

FeS + HCl

NaOH + Al2(SO3)3

NaCl + H2SO4

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Double Displacement Reactions

H2S + CuSO4

KCl + Hg2SO4

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Neutralization Reactions

• Double displacement

reactions that involve the

reaction between an acid

and base

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Neutralization Reactions

Mg(OH)2+2HCl MgCl2+2H2O

base + Acid salt + water

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Internet References

•Group work site•Balancing Equations•Tutorial in Reactions